Technologies for controlling an attitude or orbit of a flying object flying through space or the atmosphere have been developed. In a system typically called DACS (Divert and Attitude Control System), an attitude control thruster for controlling an attitude of the flying object and an orbit control thruster for changing an orbit are used for controlling the attitude and orbit.
Patent Literature 1 discloses one example of a thruster control method. The method includes: detecting a pressure of a combustion chamber, comparing the detected pressure with a predetermined pressure value, and changing discharge areas of a plurality of nozzles for substantially same amount so that the pressure of the combustion chamber becomes the predetermined pressure, based on a difference between the detected pressure and the predetermined pressure.